Power chain saw



Aug. 29, 1944. R. w. SHADE I POWER CHAIN SAW Filed June 30, 1942 INVE N70/? R05 ERT WILL/A M5/1ADE ATTORNEY Patented Aug. 29, 19%

Robert William Shade, Vancouver, British 1 Columbia, Canada ApplicationJune 30, 1942, Serial No.'449,138

3 Claims.

My invention relates to improvements in power chain saws, particularlythose which are used in the woods for bucking fallen timber.

The usual type of power chain saw is provided with a prime mover at oneend which is either a gasoline engine or an electric motor, th primemover being provided with a pair of handles by which it and the saw'ismanipulated by an operator and at the outer end of the saw another pairof handles are provided. When using the saw for bucking falln trees thehandle or handles at the outer end are of little valu and are in manycases a hindrance, since they make it diflicult to enter the free end ofthe saw cutter bar into' the place where a cut may be required. At thefree end of the usual power saw cutter bar a sheave is provided overwhich the chain saw passes and the sheave is spring mounted to provide aresilient tension on the chain saw so that shocks imparted to the saw byknots or other obstructions while cutting are'not fully transmitted tothe operator. The above construction makes the free end of the sawcumbersome and does not permit the saw to be withdrawn lengthwisethrough a cut, should it be desirable.

With a view to overcoming the above and other defects the presentinvention is designed so that no spring mounted sheave is required atthe outer end of the cutter bar, and to prevent any shock to the evenrunning of the chain saw being transmitted to the operator handling thsaw.

Referring to the drawing,

Fig. 1 is a side elevation of the invention showing a portion of thestrut cut away and exposing the drive sprocket.

Fig. 2 is a plan view.

In the drawing like characters of reference indicate corresponding partsin each figure.

The numeral I indicates a gasoline engine provided with atransmissioncase 2 on the side of which a drive sprocket 3 is mounted.The sprocket 8 is driven through a clutch 4 omitted from Figure 1, whichis operated byv a lever 5 on the opposite side of the transmission case2.

The engine has a pair of hinge brackets 6 extending horizontally forwardfrom its cylinder I and is connected by a pin 8 to a pair of brackets 8which are carried upon the strut H] of the saw. The strut is soconstructed as to provide a vertical slot I! in which is rigidly securedthe inner end of a cutter bar I3 and leave upper and lower openings l4through which an endless chain saw I! may pass.

The cutter bar I3 consists of a plate cambered upon its upper and loweredges as at It, having its free end semi-circular as at IT and its innerend arcuately tapered to less than the diameter of the driven sprocket3, as indicated at I8. The cutter bar [8 is provided with a peripheralgroove l9 indicated in dotted line in Figure .1 to receive the drivingteeth of the chain saw and form a guide track therefor in the usual way.Adjacent the outer end of the cutter bar an opening 2| is providedtoserve as a hand hole for lifting the forward end of the device whenplacing it in position upon a log or removing it from one place toanother.

Extending from the strut l 8 is a pair of handle bars 23 which areconnected together by a cross bar 24 and are fitted with handles orgrips 25 at their outer ends. A bolt 21 is hingedly connected to thebase of the strut l0 and passes through an upturned bracket 28 mountedon the base of the engine. The bolt is provided with a compressionspring 29 which urges the engine away from the strut l0 and resilientlytensions the chain saw l5 upon the cutter bar l3 and the sprocket 3. Thecompression of the spring 28 is such as to support the engine in normalposition as shown within its mounting between the handle bars 23 whenthe saw is cutting under normal load or when at rest.

In operation, the device is set with the strut in contact with the logor other work to be sawn and since the device operates on the draw outthe drag of the saw will hold the strut firmly in abutment against thework. If a knot or other temporary obstruction is encountered by thechain saw l5 the momentum and power of the engine will cause the engineI to swing aboutthe pin 8 with the sprocket 3 swinging along th areshown in dotted line in Figure 1 as at X.

The above engine movement will provide a -small amount of slack in theupper run of the chain saw, some of which will develop in a slight sag'between the sprocket 3 and the tapered inner end I8 of the cutter barl3.

The resistance to free movement of the upper run of the chain saw in thekerf will prevent any slack developing at the free end of the frame.

It is obvious that other means may be adopted to mount the engine tomove the prime mover towards and away from the strut and to providecushioning means'between said parts.

What I claim as my invention is:

1. A power driven chain saw comprising a strut having a pair of spacedsupports extending rearwardly therefrom, a cutter bar extendingtorwardly from said strut and being rigidly connected thereto, a primemover connected to the strut and having movement between the spacedsupports in' the direction of the cutter bar, a, chain saw extendingaround the cutter bar, said prime mover having a, sprocket for drivingthe chain saw and spring means interposed between the strut and theprime mover for resiliently tensioning th saw upon the cutter bar.

2; A power driven chain saw comprising a. strut having a pair of spacedsupports extending rearwardly therefrom, a cutter bar extending ior-'wardly from said strut and being rigidly connected thereto, a. bracketextending from the strut, a prime mover having a sprocket hingedlyconnected to said bracket and having movement between the spacedsupports, a chain saw surround- 10 bar, a prime mover having a sprockettor driving the chain, said prime mover being pivotally connected fromthe strut for swinging movement between said bars, and a compressionspring interposed between the strut and the prime mover 15 forresiliently tensioning the chain.

ROBERT WILLIAM SHADE.

